Transcript The Cell (including cell division)

Lab 2, BIO 105
Cell Reproduction:
• Process by which a cell divides and duplicates its
genetic information
• Includes 2 stages:
1. Interphase: period of a cell’s life when it carries
out its normal metabolic activities and grows;
o chromosomes appear as chromatin(look like dots
(chromosomes +proteins called histones)
o Nuclear membrane is intact and visible as are
the nucleoli
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2. Mitotic phase –DNA and nuclear division into 2
daughter cells
• Is subdivided into four stages:
--Prophase
--Metaphase
-- Anaphase
-- Telophase
just before nuclear division, chromatin condenses into chromatids (so they won’t
break apart during division) and are held together by centromeres.
PMAT
– Mitotic phase is essential for body growth and
tissue repair
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Prophase—divided into 2 stages
• Chromosomes become visible, each with two chromatids joined
at a centromere (Under the microscope, Chromosomes
straighten out; are more disorganized looking )
• DNA has replicated, but has not formed condensed
structure of chromosome. They remain as loosely coiled
chromatin; copies of chromatin remain attached to each
other.
• Centrosomes separate, act as areas of growth of 2
“spindles” which migrate toward opposite poles of cell.
• Mitotic spindles (microtubules) form (from centrosomes)
and push centrosomes toward opposite ends of cell
• Nuclear membrane is still intact to protect DNA
molecules from mutation.
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Metaphase
• Centromeres of chromosomes (called spindles) are
aligned at opposite poles of cell
• Chromosomes line up at middle of the cell, called
metaphase plate or equator or equatorial plate
Anaphase
• Separated sister chromatids are pulled along behind
centromeres and move to opposite cell ends. (“V” for
victory sign)
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Telophase
• Begins when chromosome movement stops
• Two sets of chromosomes uncoil to form chromatin
• New nuclear membrane forms around each chromatin mass
• Nucleoli reappear
• Spindle disappears
Cytokinesis—division of cytoplasm so 2 new daughter cells are
formed
– Actually begins at end of Anaphase
– Ring of actin microfilaments contracts to form a cleavage
furrow and pinches apart so 2 daughter cells form
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LABWORK
1. Identify the different stages of mitosis on
microscope slides.
2. Describe process of DNA replication and
mitosis.
3. Study process of mitosis models. [cell models]
4. Be able to identify interphase and each stage
of mitosis on models and slides.
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